1. Field of the Invention
The present invention relates to a power supply apparatus for electronic equipment, and more specifically relates to a power supply apparatus that is useful for supplying electric power to a portable electronic equipment, such as a wrist watch or a mobile telephone, and to electronic equipment that uses the power supply apparatus.
2. Description of the Prior Art
In general, a battery is provided in portable electronic equipment, such as a wrist watch or a mobile telephone, to supply electric power thereto. For instance, a button-type (coin-type) battery is used for a wrist watch and a rechargeable battery that is charged using a transmitted AC power supply is used for a mobile telephone.
However, in the case where there is used a non-rechargeable battery such as a button-type battery or a dry battery, a supply voltage is gradually reduced due to a usage thereof or a secular variation, which leads to a problem that it is required to frequently perform battery exchanging.
On the other hand, in the case of a rechargeable battery, it is necessary to remove the battery from the casing of a portable electronic equipment and set the battery in a battery charger. Also, in the case where battery charging is performed by setting the battery in the charger without removing the battery from the casing, it takes around several to 10 hours to perform the battery charging. As a result, there occurs a problem that the charging operation is burdensome.
Incidently, the number of portable communication terminals has been rapidly increased in recent years, with the result that radio waves (electric fields, magnetic fields) are surely increased in urban spaces. In addition, the usable frequencies are shifted to high frequencies, which results in a situation where spatial electric fields have become higher than ever. In more detail, new usable frequencies are shifted to a GHz band or higher, which leads to a situation where the electric fields exceed 100 dBxcexcV/m in general. It is believed that this trend will be continuously accelerated at a considerable momentum for the moment by the introduction of the WCDMA system into the mobil telephone field and the widespread use of cordless telephones based on the PHS system at homes in the future.
Consequently, in view of the problems and the situation of spatial electric fields described above, the object of the present invention is to provide a power supply apparatus that replaces a dry battery by detecting/rectifying electric field energy in a free space, extracting the energy as electric power, and accumulating the electric power. In particular, the object of the present invention is to provide a power supply apparatus that is useful for a portable electronic equipment.
In order to achieve the above-mentioned object, a power supply apparatus according to the present invention is characterized by comprising: an electromagnetic energy conversion unit for collecting electromagnetic energy of a radio wave, which propagates in the air, and converting the electromagnetic energy into electric power; a rectifier unit for rectifying the electric power having an AC waveform inputted from the electromagnetic energy conversion unit and outputting electric power having a DC waveform; a storage battery that is charged with the rectified electric power having the DC waveform and discharges the charged electric power; and a control unit for controlling the charging and discharging of the storage battery.
Therefore, it is possible to collect a radio wave propagating in the air, convert collected electromagnetic energy into electric power, generate electric power having a DC waveform by rectifying electric power having an AC waveform, charge the rectified electric power having the DC waveform into a storage battery, and supply an electric load with the rectified electric power having the DC waveform or with electric power having a DC waveform discharged from the storage battery.
In this case, it is possible to employ a structure such that a power supply apparatus comprises: a first input terminal that contacts a human body and inputs the electromagnetic energy of the radio wave propagating in the air via the human body; and a second input terminal that connects a ground of an electronic circuit within the apparatus to the human body, wherein the rectifier unit rectifies the electric power having the AC waveform inputted from the electromagnetic energy conversion unit and the input terminal, and outputs the electric power having the DC waveform.
Also, a power supply apparatus according to the present invention is characterized by comprising: an electromagnetic energy conversion unit for collecting electromagnetic energy of a radio wave, which propagates in the air, and converting the electromagnetic energy into electric power; an input terminal that contacts a human body and inputs electromagnetic energy of a radio wave propagating in the air via the human body; a rectifier unit for rectifying the electric power having an AC waveform inputted from the electromagnetic energy conversion unit or the input terminal and outputting electric power having a DC waveform; a storage battery that is charged with the rectified electric power having the DC waveform and discharges the charged electric power; and a control unit for controlling the charging and discharging of the storage battery.
Also, a power supply apparatus according to the present invention is characterized by comprising: an input terminal that contacts a human body and inputs electromagnetic energy of a radio wave propagating in the air via the human body; a rectifier unit for rectifying electric power having an AC waveform inputted from the input terminal and outputting electric power having a DC waveform; a storage battery that is charged with the rectified electric power having the DC waveform and discharges the charged electric power; and a control unit for controlling the charging and discharging of the storage battery.
In this case, a structure may be adopted such that the input terminal includes a positive electrode terminal and a negative electrode terminal that contact the human body, and the positive electrode terminal and the negative electrode terminal are formed so that one of the terminals has a circular shape, whose center is the other of the terminals, or both of the terminals have a dotted shape.
Also, a structure may be adopted such that a power supply apparatus further comprises a matching unit that establishes impedance matching between a rectifier unit side and one of the electromagnetic energy conversion unit and the input terminal.
Also, a structure may be adopted such that the matching unit is constructed from a resistance.
Also, a structure may be adopted such that the matching unit is a serial resonance circuit constructed from a capacitor and an inductor.
Also, a structure may be adopted such that the matching unit is a parallel resonance circuit constructed from a capacitor and an inductor.
Also, a structure may be adopted such that the control unit includes: two backflow prevention rectifier elements that perform rectification toward the storage battery at a subsequent stage; and a voltage step-up circuit that steps up, to a predetermined value, a voltage of the electric power having the DC waveform connected to an input terminal side of one of the backflow prevention rectifier elements.
Also, a structure may be adopted such that the control unit includes: an input voltage monitoring means for monitoring an input voltage of the electric power having the DC waveform inputted from the rectifier unit; and a monitoring means for, if the input voltage is higher than the predetermined value, terminating an operation of the voltage step-up circuit so that the inputted electric power having the DC waveform is directly supplied to the storage battery and, if the input voltage is lower than the predetermined value, controlling an operation of the voltage step-up circuit so that the input voltage is stepped up by the voltage step-up circuit and is supplied to the storage battery.
Also, a structure may be adopted such that the control unit further includes a storage battery voltage monitoring means for monitoring a storage battery voltage on the storage battery side, and if the storage battery voltage is a predetermined value or more, the monitoring means terminates driving of the voltage step-up circuit.
Also, a structure may be adopted such that the voltage step-up circuit provided for the control unit is of a switched capacitor type constructed by connecting a switch element to a capacitor, and the voltage step-up circuit is provided with an oscillation circuit that oscillates a clock signal for controlling timing of a step-up operation of a voltage.
Also, a structure may be adopted such that a buffer circuit is provided to follow the oscillation circuit, the buffer circuit amplifying a potential at one end of the capacitor in accordance with the clock signal, a power supply of the buffer circuit is connected to an output side of the rectifier unit, and the buffer circuit is operated by the electric power having the DC waveform that is transmitted from the electromagnetic energy conversion unit via the matching unit and the rectifier unit.
Also, a structure may be adopted such that the electromagnetic energy conversion unit is a flat antenna obtained by overlaying a back plane, an insulating layer, and an antenna conductor on a cross-sectional lower layer.
Also, a structure may be adopted such that the antenna conductor is formed using one of a circular pattern, a rectangular pattern, and another flat pattern.
Also, a structure may be adopted such that the antenna conductor has a construction where a wiring pattern is allowed to extend from the flat pattern and is arranged at a position at which the wiring pattern also opposes the back plane.
Also, a structure may be adopted such that the flat pattern and the wiring pattern are formed so as to become a same plane.
Also, a structure may be adopted such that the flat pattern and the wiring pattern are formed so as to have one of a stepped surface and an inclined surface.
Also, a structure may be adopted such that the wiring pattern is arranged on the insulating layer.
Also, a structure may be adopted such that the flat antenna is formed so as to have one of a flat plate shape, a bent shape, and a ring shape.
Also, a structure may be adopted such that the electromagnetic energy conversion unit is one of a whip antenna using a spiral electric wire and a dielectric antenna using a dielectric.
Also, a structure may be adopted such that the rectifier unit includes a half wave voltage doubler rectifier circuit constructed from a first diode and a second diode that are connected in a forward direction.
Also, a structure may be adopted such that If/IR of one of the first and second diodes that is connected to the storage battery side is smaller than If/IR of the other of the first and second diodes.
Also, a structure may be adopted such that the rectifier unit includes a single diode and an inductor that gives a bias to the diode.
Also, a structure may be adopted such that the rectifier unit includes: a diode whose anode is connected to a ground side and cathode is connected to an AC signal side; a xcex/4 line whose one end is connected to a cathode of the diode; a conductor that is arranged so as to oppose the xcex/4 line; and a capacitor that is connected between the other end of the xcex/4 line and a ground.
Also, a structure may be adopted such that the rectifier unit includes a MOSFET that substitutes for the diode.
Also, an electronic equipment according to the present invention has a structural characteristic of including a power source apparatus of the present invention, the power source apparatus supplying an electric power having a DC waveform to the electronic equipment.